This invention relates to the handling and processing of printed paper products, such as brochures and the like, and especially to the automatic folding of such products. More particularly, the invention relates to machines for making a gate fold in a prefolded sheet.
The invention has particular utility with respect to thrice-folded sheets containing four leaves, wherein the two outer leaves are folded inward initially along two parallel fold lines and the resulting folded sheet is again folded along its transverse centerline to form a brochure sheet or the like with four leaves or, in other words, with eight pages. The center fold, which is known in the art as a "gate fold," presents certain problems in automatic folding operations, particularly in view of the two prefolded, inwardly extending end leaves.
Prior art folding machines for making gate folds are best known as "tape and knife" type machines. Normally, these machines are equipped with automatic feeders that feed the sheets one-at-a-time. The sheet rides on endless traveling tapes up to a locator stop, where it is positioned just over a pair of parallel, knurled fold rolls forming a nip. At this point, a folding knife or blade descends from above to drive the sheet down between the nip formed by the knurled fold rolls to cause the sheet to be folded in the middle and drawn downward between the rolls.
The use of such machines has presented certain difficulties in the past, especially those encountered in setting up the apparatus, which often requires as much as half a day. Also, the machines currently available tend to produce random defects such as dog-eared gate folds or roll-back folds.
The apparatus of the present invention, however, overcomes many of the difficulties indicated above, and affords other features and advantages heretofore not obtainable.